We propose to undertake computational studies of rhythmic oscillations during quiet sleep in the thalamus. A biophysical network model of the thalamic circuitry is being constructed, issues that are investigated include the rhythmogenesis of the 10 Hz thalamic spindle oscillations and wave propagations, the cellular basis of various slow oscillatory modes and synaptic mechanisms of synchronization, and origin of variability and intermittency in thalamic neuronal firing patterns. The proposed modeling of the thalamic network is designed to elucidate the physiological basis for sleep rhythms and their neuromodulation in the thalamocortical system. It could also subserve a first step in computational studies of the dynamical operations in the thalamocortical circuitry, especially on the role of temporal simultaneity(as embedded by cooperative oscillations) in the organization of perception and behavior.